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luis
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Re: My 38 dilemma

Wed Sep 07, 2022 9:32 pm

antique diver wrote:
Wed Sep 07, 2022 9:17 am
luis wrote:
Tue Sep 06, 2022 10:00 pm
With 21% if it has any rust it should be light.

How do they sound when you hit them with any type of metal object, a hammer will do. That is called a hammer test and it should be done on steel cylinders before filling. Just a light tap. A steel cylinder should sound clear as a bell. Any substantial rust will make a cylinder sound dull.

If they sound clear as a bell and with 21%, you should go dive them before you empty them. The 1980 air is much better air than you will find now-a-days. That is unless it was filled with a poorly maintained gasoline compressor or something like that, but that is unlikely.

I would dive them. :)


BTW, You should replace that burst or at least removed them (if you are not going to use the valve). Those lead plugs just scare the heck of me. I have seen of them go. They can do some damage, like a bullet.


Good luck.

If you are testing for a clear ring tone I think it is best done with the bands off to get a true idea of condition. They can damper the tone. Of course that would be best done with empty tanks to eliminate danger of stressing the manifold. Attempting this with full pressure will require a lot of caution and stabilizing the tank positions where that couldn't vary from the banded positioning.

Luis, your thoughts on this subject?

That is a very good point about the bands.


So Mark, how did it sound, when you hit the speed bumps? with the sledge hammer?
Luis

Buceador con escafandra autónoma clásica.

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luis
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Re: My 38 dilemma

Wed Sep 07, 2022 9:44 pm

OK, So you really got me curious about the sound with the bands on double cylinders. So, I had to go upstairs where I have 4 pairs of doubles, 4 different sizes. One pair of steel 72 and the others are all smaller (shorter).

I only used a big metal screwdriver to hit lightly between the bands. They all sound clear as a bell. The really cool thing is that they all have slightly different tone. I which that I was more musically inclined or talented... I could have really had fun playing some tunes.

The tone on both cylinder of the same pair seem to match perfectly, but all 4 pairs are different size and pressure (probably slightly different wall thickness). So each pair had its own tune.


If you have ever seen a special on how they tune steel drums for a Calypso band, by forming the end of a 55 gallon drum into a musical instrument... it is fascinating.

Again, I am not talented enough to make a musical instrument out of 4 pair of cylinders, but it was cool to notice the different notes.
Luis

Buceador con escafandra autónoma clásica.

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ScubaLawyer
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Re: My 38 dilemma

Wed Sep 07, 2022 11:30 pm

So Mark, how did it sound, when you hit the speed bumps? with the sledge hammer?
Sound with the hammer between the bands was actually kinda dull. Kind of a squishy sound with the speed bump. Turned out the speed bump wasn't asphalt, just a large raccoon. :)
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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